Tightening member for filaments



Nov. 13, 1956 MOESKER I 2,770,753

TIGHTENING MEMBER FOR FILAMENTS Filed Oct. 16, 1952 INVENTOR GERARD MOESKER AGENT United States Patent-O TIGHTENING MEMBER FOR FILAMENTS Gerard Moesker, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee; patent dedicated to the Public insofar as it relates to lamps and lamp parts to the extent stated in document recorded in the United States Patent Oflice April 13, 1954 Application October 16, 1952, Serial No. 315,079

Claims priority, application Netherlands November 23, 1951 Claims. (Cl. 313278) The invention relates to a tightening member for filaments, such as heating wires, incandescent cathodes and filaments for electrical apparatus including electric discharge tubes and incandescent lamps, and to apparatus comprising such a tightening member.

For tightening such filaments, particularly filamentous cathodes it has been suggested to use a tightening device comprising a resilient part atleast one limb of which passes several times helicallyaround a support and has its end secured to a separate securing member, the support and the securing member being each united with a stay pole of the electrode system of a tube or incandescent lamp, for example by welding. The resilient part may alternatively be formed as a loop having the support as a base, the top being united with the filament to be tightened. The loop being made by winding a hairpin-like wire end several times around a mandrel, the free ends of the limbs being then interconnected by means of a securing member. The mandrel is subsequently replaced by a support shaped in the form of a short bar. This support is welded to a stay pole of the electrode system of a tube or lamp, the securing member being then also welded to the said stay pole so that the filament is given a certain bias.

Since tightening members of the above-described kind are generally of small size this device is complicated and time-consuming since the support and the resilient part are required to be assembled and separately mounted. According to the invention this ditficulty is obviated if such a tightening member, which is constituted by a resilient part, at least one limb of which passes several times helically about the support and has its end joined to a separate securing member. The securing member and the support are rigidly interconnected by means of a linking member so that the tightening member constitutes a unitary piece which is independently adaptable for use. This enables the tightening member to be secured as a whole by means of the securing member to a stay pole with the use of a single weld. Preferably, use is also made of a loop-shaped resilient part similar to the known embodiment referred to. In addition, it is possible to form a number of adjacent resilient loops, for example, for tightening a plurality of parallel filaments, or a filament constituted by a plurality of hairpin-shaped parts.

In order that the invention may be more clearly understood and readily carried into elfect, it will now be described in detail with reference to the accompanying drawing, in which:

Fig. 1 shows a discharge tube comprising a tightening member according to the invention,

Figs. 2 and 3 show alternative embodiments of tightening members according to the invention, and

Figs. 4, 5, 6, 7 and 8 show the manufacture of several tightening members embodying the present invention.

Referring to Fig. 1, a discharge tube 1 comprises an electrode system 2 including 2. directly heated filamentous incandescent cathode 3. The cathode: 3 is kept taut by a tightening member in accordance with the invention, comprising a resilient part in the form of a loop 4, the limbs of which are helically wound several times about a support 5. The turns 6 and 7 are wound in opposite senses. The ends 8 and 9 respectively of the turns 6 and 7 respectively are welded to a separate securing element 10, which in turn is united to the support 5 by a linking member 11 so that prior to attachment to the stay pole 12 the tightening member constitutes a unitary piece which is independently adaptable for use. The linking member 11, which forms part of the securing element 10, is secured to the support 5 at a portion which is located between the turns 6 and 7.

As an alternative, the tightening member may be divided into two parts so as to form members as shown in Fig. 2. The resilient part 13 is bent at the end to form a hook and, subsequently to the filament being placed in position, occupies the position 13" shown in dotted lines. This consequently always results in identical stressing force, since the resilient parts are invariably bent from the unstressed position by approximately Fig. 3 shows a double tightened spring. Obviously, the tags 11 may alternatively be secured to the support 5 opposite the loops 14 and 15.

Referring more particularly to Figs. 4, 5 and 6 which shows how the tightening members embodying the present inventionare manufactured in quantity, in which use is madeof a continuous support 16 which may be cylindrical or band-shaped. The helical turns 17 are produced by winding a steel wire alternately in clockwise direction and in a counter-clockwise direction so that a loop 18 and 19 respectively are formed successively between these windings, said loops being preferably comprised in one plane but at opposite sides of the support 16. A strip 20 which is provided with linking members in the form of tags 21 is then welded itself to the loops 19 and by means of the tags 21 to the support 16, separate tightening members of the kind shown in Fig, 1 being then produced by severing or dividing along the lines 22, it being possible for the members shown in Fig. 2. to be produced by dividing along the lines 222422. Members comprising two loops may be obtained by dividing along the lines 22, 23. For the manufacture of members as shown in Fig. 3, provision must be made for the linking members 21 shown in Fig. 5.

As an alternative, the linking members 25 may form part of the support 26 which in this case is preferably bandshaped (Fig. 6). The securing elements are then produced from a strip 27 which has been welded to the linking members 25 and the loops 28. However, it is necessary for the support and the securing element to be separate parts, since otherwise automatic winding of the stressing spring cannot be effected in a simple manner.

Referring to Fig. 7 separate securing elements 29, each comprising a linking member 30, are inserted in a clamping holder 31 and then welded to the loops 19. The linking members 30 are secured to the support 16.

The loops need not register with each other but may be wound at an angle or they may be arranged all on the same side of the support (33 and 34 in Fig. 8). In the latter case, narrow securing elements 32 may be attached to non-succeeding loop 34. Dividing along the lines 35 enables tightening members as shown in Fig. 2 to be produced, the stressing spring being, however, in the operating position bent through an angle exceeding 90.

Obviously, other embodiments of the invention may be designed; thus, for example, the linking member may be constituted by a separate part which is secured both to the support and to the securing element.

While I have shown and described the preferred embodiment of my invention, it will be understood that the latter may be embodiment otherwise than as herein specifically illustrated or described and that in the illustrated embodiment certain changes in the details of construction and in the arrangement of parts may be made without departing from the underlying idea or principle of the invention within the scope of the appended claims.

What I claim is:

1. A tightening device for filaments of an electrical apparatus comprising a support, a securing element being provided With a linking member fixedly secured to said support thus forming a unitary structural piece, a resilient member having part thereof adjacent one end helically Wound about said support, and the one end of said resilient member being secured to said securing element, and a stay pole, means connecting said securing element to said stay pole.

2. A tightening device for filaments of an electrical apparatus comprising a support, a securing element being provided with a linking member integral therewith and fixedly secured to said support thus forming a unitary structural piece, a resilient member having a part thereof adjacent one end helically wound about said support, and the one end of said resilient member being secured to said securing element, and a stay pole, means connecting said securing element to said stay pole.

3. A tightening device for maintaining at least one filamentous filament of an electrical apparatus in a taut condition comprising a cylindrical rod-like support, a flat securing element being provided with a linking member fixedly secured to said support thus forming a unitary structural piece, a resilient member having part thereof adjacent one end helically wound about said support, and

the one end of said resilient member being Welded to said securing element, and a stay pole, means connecting said securing element to said stay pole.

4. A tightening device for filaments of an electrical apparatus comprising a support, a securing element being provided with a linking member fixedly secured to said support thus forming a unitary structural piece, a resilient member having one end secured to said securing element and the other end operatively connected to said filament thus tensioning the latter, and a part of said resilient member intermediate of the ends thereof being spirally wound about said support, and a stay pole, means connecting said securing element to said stay pole.

S. A tightening device for filaments of an electrical apparatus comprising a support, a flat securing element being provided with an integral linking member fixedly secured to said support, a resilient member having two portions thereof helically wound about said support and a part thereof intermediate of said two helically wound portions forming a loop and being attached to a filament thus tensioning the latter, and the free ends of said resilient member being secured to said securing element, and a stay pole, means connecting said securing element to said stay pole.

References Cited in the file of this patent UNITED STATES PATENTS Carlstrom Mar. 16, 1954 

